The following discussion of the background of the invention is merely provided to aid the reader in understanding the invention and is not admitted to describe or constitute prior art to the present invention.
The clinical presentation of certain diseases can often be strikingly similar, even though the underlying diseases, and the appropriate treatments to be given to one suffering from the various diseases, can be completely distinct. For example, subjects may present in an urgent care facility exhibiting a deceptively simple constellation of apparent symptoms (e.g., fever, shortness of breath, dizzyness, headache) that may be characteristic of a variety of unrelated conditions. Differential diagnosis methods involve the comparison of symptoms and/or diagnostic test results known to be associated with one or more diseases that exhibit a similar clinical presentation to the symptoms and/or diagnostic results exhibited by the subject, in order to identify the underlying disease or condition present in the subject.
Taking shortness of breath (referred to clinically as “dyspnea”) as an example, patients often present in a clinical setting with this symptom as the initial clinical presentation. This symptom considered in isolation may be indicative of conditions as diverse as asthma, chronic obstructive pulmonary disease (“COPD”), tracheal stenosis, obstructive endobroncheal tumor, pulmonary fibrosis, pneumoconiosis, lymphangitic carcinomatosis, kyphoscoliosis, pleural effusion, amyotrophic lateral sclerosis, congestive heart failure, coronary artery disease, myocardial infarction, cardiomyopathy, valvular dysfunction, left ventricle hypertrophy, pericarditis, arrhythmia, pulmonary embolism, metabolic acidosis, chronic bronchitis, pneumonia, anxiety, sepsis, aneurismic dissection, etc. See, e.g., Kelley's Textbook of Internal Medicine, 4th Ed., Lippincott Williams & Wilkins, Philadelphia, Pa., 2000, pp. 2349-2354, “Approach to the Patient With Dyspnea”; Mulrow et al., J. Gen. Int. Med. 8: 383-92 (1993).
Differential diagnosis in the case of dyspnea involves identifying the particular condition causing shortness of breath in a given subject from amongst numerous possible causes. These methods often require that the clinician integrate information obtained from a battery of tests, leading to a clinical diagnosis that most closely represents the range of symptoms and/or diagnostic test results obtained for the subject. The tests required may include radiography, electrocardiogram, exercise treadmill testing, blood chemistry analysis, echocardiography, bronchoprovocation testing, spirometry, pulse oximetry, esophageal pH monitoring, laryngoscopy, computed tomography, histology, cytology, magnetic resonance imaging, etc. See, e.g., Morgan and Hodge, Am. Fam. Physician 57: 711-16 (1998). Because of the variety of tests that may need to be performed, obtaining sufficient information to arrive at a diagnosis can take hours or even days.
Differential diagnosis of chest pain requires the clinician to consider many possible causes, including differentiating between respiratory pain and pain associated with angina, or myocardial infarction and pleuritic and chest wall pain.
Differential diagnosis of diastolic and systolic dysfunction in patients suffering from heart failure is important since the therapies for each dysfunction are different. Further differentiation of atrial fibrillation from heart failure is critical for appropriate therapy.
In the area of infection, diffential diagnosis of viral versus bacterial is critical to the clinician delivering the appropriate therapy.
The acuteness or severity of the symptoms often dictates how rapidly a diagnosis must be established and treatment initiated. Immediate diagnosis and care of a patient experiencing a variety of acute conditions associated with dyspnea and chest pain can be critical. See, e.g., Harris, Aust. Fam. Physician 31: 802-06 (2002) (asthma); Goldhaber, Eur. Respir. J. Suppl. 35: 22s-27s (2002) (pulmonary embolism); Lundergan et al., Am. Heart J. 144: 456-62 (2002) (myocardial infarction). However, even in cases where the apparent symptoms appear relatively stable, rapid diagnosis, and the rapid initiation of treatment, can provide both relief from immediate discomfort and advantageous improvement in prognosis.
Each reference cited in the preceeding section is hereby incorporated by reference in its entirety, including all tables, figures, and claims.